CN117949860A - LED (light-emitting diode) access state detection circuit - Google Patents

LED (light-emitting diode) access state detection circuit Download PDF

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Publication number
CN117949860A
CN117949860A CN202410058980.4A CN202410058980A CN117949860A CN 117949860 A CN117949860 A CN 117949860A CN 202410058980 A CN202410058980 A CN 202410058980A CN 117949860 A CN117949860 A CN 117949860A
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China
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led
path
short
voltage
state
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CN202410058980.4A
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叶为熙
李萌
欧晓晴
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On Bright Electronics Shanghai Co Ltd
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On Bright Electronics Shanghai Co Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
    • G01R31/52—Testing for short-circuits, leakage current or ground faults
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
    • G01R31/54—Testing for continuity

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Led Devices (AREA)

Abstract

The invention provides an LED access state detection circuit, which comprises: and a short/open time division multiplexing detection module configured to serially determine whether the LED path is in a path short state and whether the LED path is in a path open state based on a first path voltage, a short determination reference voltage, and an open determination reference voltage of the LED path.

Description

LED (light-emitting diode) access state detection circuit
Technical Field
The invention relates to the field of circuits, in particular to an LED (light-emitting diode) access state detection circuit.
Background
Light Emitting Diode (LED) backlighting is a new type of backlighting display technology. Compared with a Liquid Crystal Display (LCD) adopting the traditional backlight technology, the LCD adopting the LED backlight technology has better performance in dynamic contrast ratio and brightness, and has the advantages of light weight, high image quality, low power consumption and the like. The problems of short circuit, open circuit and the like of the LED channels can cause LED damage, and if the LED is damaged, the screen is required to be disassembled for maintenance, so that the reliability requirement on LED protection is higher, and meanwhile, the realization mode of the LED protection function is required to be as simple as possible due to the limitation of the occupied area and the power consumption of the LED backlight driving circuit.
Disclosure of Invention
According to an embodiment of the invention, an LED channel state detection circuit comprises: and a short/open time division multiplexing detection module configured to serially determine whether the LED path is in a path short state and whether the LED path is in a path open state based on a first path voltage, a short determination reference voltage, and an open determination reference voltage of the LED path.
Drawings
The invention will be better understood from the following description of specific embodiments thereof, taken in conjunction with the accompanying drawings, in which:
Fig. 1 shows a schematic block diagram of a conventional LED path state detection circuit.
Fig. 2 shows a circuit schematic of a conventional LED path state detection circuit.
Fig. 3 shows a schematic block diagram of an LED via status detection circuit according to an embodiment of the invention.
Fig. 4 shows a flowchart of the operation of the LED path state detection circuit shown in fig. 3.
Fig. 5 shows an example circuit diagram of an LED via status detection circuit according to an embodiment of the invention.
Fig. 6 shows an operation timing chart of a plurality of signals in the LED channel state detection circuit shown in fig. 5.
Detailed Description
Features and exemplary embodiments of various aspects of the invention are described in detail below. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the invention by showing examples of the invention. The present invention is in no way limited to any particular configuration and algorithm set forth below, but rather covers any modification, substitution, and improvement of elements, components, and algorithms without departing from the spirit of the invention. In the drawings and the following description, well-known structures and techniques have not been shown in order to avoid unnecessarily obscuring the present invention. In addition, the term "a and B connected" as used herein may mean "a and B directly connected" or "a and B indirectly connected via one or more other elements".
Currently, an LED backlight driving circuit uses a comparator module to determine an LED path state (e.g., a path short state, a path open state, and a path voltage deviation state) by detecting a path voltage of an LED path.
Fig. 1 shows a schematic block diagram of a conventional LED path state detection circuit. In the LED path state detection circuit 100 shown in fig. 1, the short-circuit determination comparator module determines whether the LED path is in a path short-circuit state based on the first path voltage V LED of the LED path; the open circuit judgment comparator module judges whether the LED channel is in a channel open circuit state or not based on the second channel voltage V FB of the LED channel; the path voltage comparator module determines whether the LED path is in a path voltage deviation state based on the path voltage V FB of the LED path. The first path voltage V LED and the second path voltage V FB of the LED path are voltages on the drain and source of the high voltage isolation tube M HV, respectively, the high voltage isolation tube M HV being connected between the LED path and ground and being turned on or off under control of a Pulse Width Modulation (PWM) signal for controlling the LEDs in the LED path to be turned on or off.
Fig. 2 shows a circuit schematic of a conventional LED path state detection circuit. In the LED channel state detection circuit 200 shown in fig. 2, the comparator COMP1 determines whether the LED channel is in a channel voltage deviation state based on the channel voltage V FB of the LED channel; the comparator COMP2 judges whether the LED path is in the path open state based on the second path voltage V FB of the LED path; the switching tube M3 is turned on or off under the control of a PWM signal for controlling the on or off of the LEDs in the LED path; when the switching tube M3 is in a conducting state, the first channel voltage V LED of the LED channel is divided by the voltage dividing resistors R1 and R2 to obtain a divided voltage V LED_div; when the PWM signal for controlling the on or off of the LEDs in the LED path is at a logic high level (i.e., when the LEDs are in an on state), the switching tube M3 is in an on state, and the comparator COMP3 determines whether the LED path is in a path short state based on the divided voltage V LED_div. The first path voltage V LED and the second path voltage V FB of the LED path are voltages on the drain and source of the switching transistor M1 (the switching transistor M1 is a high-voltage isolation tube), respectively, and the switching transistor M1 is connected between the LED path and ground.
As described in connection with fig. 1 and 2, the use of comparator modules with parallel judgment mechanisms can accomplish the judgment of the short-circuit, open-circuit, and voltage deviation of the LED path, but the use of multiple comparator modules increases the system cost and power consumption as a whole.
In view of the above-described problems, an LED path state detection circuit according to an embodiment of the present invention is proposed that can realize determination of LED path state with relatively low system cost and power consumption by multiplexing a comparator module and adopting a serial determination mechanism.
Fig. 3 shows a schematic block diagram of an LED via status detection circuit according to an embodiment of the invention. As shown in fig. 3, the LED channel state detection circuit 300 includes a short/open time division multiplexing detection module 302 and a channel voltage comparator module 304, wherein: the short/open time division multiplexing detection module 302 is configured to serially determine whether the LED path is in a path short state and whether the LED path is in a path open state based on the first path voltage V LED of the LED path, the short determination reference voltage vref_short, and the open determination reference voltage vref_open.
As shown in fig. 3, in some embodiments, the LED channel state detection circuit 300 further includes a channel voltage comparator module 304 configured to determine whether the LED channel is in a channel voltage deviation state based on the second channel voltage V FB of the LED channel and the voltage deviation reference voltage vref_fb.
As shown in fig. 3, in some embodiments, the first and second path voltages V LED and V FB of the LED paths are voltages on the drain and source, respectively, of a high voltage isolation tube M HV, the high voltage isolation tube M HV being connected between the LED path and ground and turned on or off under control of a PWM signal for controlling the LEDs in the LED path to be turned on or off.
Fig. 4 shows a flowchart of the operation of the LED path state detection circuit shown in fig. 3. As shown in fig. 4, the workflow of the LED path state detection circuit shown in fig. 3 includes: s402, when the PWM signal for controlling the turning on or off of the LEDs in the LED channels changes from a logic low level to a logic high level (i.e., when the LEDs change from the off state to the on state), the LED channel state detection circuit 300 starts detection; s404, the short circuit/open circuit time division multiplexing detection module 302 selects the short circuit judgment reference voltage Vref_short as the reference voltage, and compares the first channel voltage V LED of the LED channel with the short circuit judgment reference voltage Vref_short; s406, if V LED > vref_short, the Short/open time division multiplexing detection module 302 generates a Short state indication signal (e.g., led_short=1) indicating that the LED path is in a path Short state and proceeds to S412; s408, if V LED is less than or equal to Vref_short, the short/open time division multiplexing detection module 302 selects the open judgment reference voltage Vref_open as a reference voltage and compares the first path voltage V LED of the LED path with the open judgment reference voltage Vref_open (i.e., in the case of judging that the LED path is not in a path short state, judging whether the LED path is in a path open state based on the first path voltage V LED and the open judgment reference voltage Vref_open); s410, if V LED < vref_open, the short/open time division multiplexing detection module 302 generates an open state indication signal (e.g., led_open=1) indicating that the LED path is in the open state of the path and proceeds to S412; s412, the short/open time division multiplexing detection module 302 ends the detection; s414, the LED-path state detection circuit 300 stops detection when the PWM signal for controlling the turning on or off of the LEDs in the LED path changes from a logic high level to a logic low level (i.e., when the LEDs change from an on state to an off state). It should be noted that the LED-path state detection circuit 300 performs the above-described detection process during the period in which the PWM signal for controlling the LEDs in the LED paths to be turned on or off is at a logic high level (i.e., during the period in which the LEDs are in the on state).
Fig. 5 shows an example circuit diagram of an LED via status detection circuit according to an embodiment of the invention. As shown in fig. 5, the LED-path state detection circuit 500 includes a path voltage comparator COMP1 and a short/open time division multiplexing detection module 502, which are in an enabled state or a disabled state under the control of a PWM signal for controlling the LEDs in the LED path to be turned on or off. It should be noted that, the via voltage comparator COMP1 may be implemented as an example of the via voltage comparator module 304, and the short/open time division multiplexing detection module 502 may be implemented as an example of the short/open time division multiplexing detection module 302.
As shown in fig. 5, in some embodiments, the short/open time division multiplexing detection module 502 includes an alternative multiplexer MUX1 and a short/open judgment multiplexing comparator COMP2. The alternative multiplexer MUX1 is configured to select one of the short circuit judgment reference voltage vref_short and the open circuit judgment reference voltage vref_open as the judgment reference voltage vref_2 under control of the two-frequency signal pwm_1 of the PWM signal for controlling the turning on or off of the LEDs in the LED path. The short/open judgment multiplexing comparator COMP2 is configured to generate a short state indication signal led_short indicating whether the LED path is in a path short state or an open state indication signal led_open indicating whether the LED path is in a path open state, based on the judgment reference voltage vref_2 and the first path voltage V LED of the LED path.
As shown in fig. 5, in some embodiments, the input signals a and B of the alternative multiplexer MUX1 are the short circuit determination reference voltage vref_short and the open circuit determination reference voltage vref_open, respectively, the control signal S of the alternative multiplexer MUX1 is the divided-frequency signal pwm_1 of the PWM signal for controlling the on or off of the LEDs in the LED channels, the inverted signal S ' of the control signal S is pwm_1', and the output of the alternative multiplexer MUX1 is out=a×s+b×s '.
As shown in fig. 5, in some embodiments, the short/open time division multiplexing detection module 502 further includes transmission gates TG1 and TG2. The transmission gate TG1 is configured to output a short-circuit state indication signal led_short indicating whether the LED path is in a path short-circuit state under control of a binary signal pwm_1 of a PWM signal for controlling the on or off of the LEDs in the LED path. The transmission gate TG2 is configured to output an open state indication signal led_open indicating whether the LED path is in an open state of the path under control of an inverted signal pwm_1' of a binary signal pwm_1 of a PWM signal for controlling the turning on or off of the LEDs in the LED path.
As shown in fig. 5, in some embodiments, the short/open time division multiplexing detection module 502 further includes a switching tube M3 and voltage dividing resistors R1 and R2, where the switching tube M3 is turned on or off under the control of a PWM signal for controlling the LEDs in the LED channels, and the voltage dividing resistors R1 and R2 divide the first channel voltage V LED of the LED channels when the switching tube M3 is in the on state to obtain the divided voltage V LED_div. In this case, the short/open judgment multiplexing comparator COMP2 generates a short or open state indication signal indicating whether the LED path is in a path short state or a path open state based on the divided voltage V LED_div of the first path voltage V LED of the LED path and the judgment reference voltage vref_2 from the one-out-of-the-path multiplexer MUX 1.
As shown in fig. 5, in some embodiments, the channel voltage comparator COMP1 is configured to generate a voltage deviation indication signal led_fb indicating whether the LED channel is in a channel voltage deviation state based on the voltage deviation reference voltage vref_fb and the second channel voltage V FB of the LED channel, wherein when V FB < vref_fb, led_fb is 1, indicating that the LED channel is in a channel voltage deviation state. The first path voltage V LED and the second path voltage V FB of the LED path are voltages on the drain and the source of the switching transistor M1 (the switching transistor M1 is a high-voltage isolation transistor), respectively, and the switching transistor M1 is connected between the LED path and the ground and turned on or off under the control of a PWM signal for controlling the on or off of the LEDs in the LED path.
Fig. 6 shows an operation timing chart of a plurality of signals in the LED channel state detection circuit shown in fig. 5. As shown in fig. 6, during the slow drop of the divided voltage V LED_div of the first path voltage V LED of the LED path from the larger voltage value to 0: in the period T1, the PWM signal is at a logic high level, COMP2 is enabled, PWM_1 is at a logic high level, vref_2=Vref_short, TG1 transmits signals, V LED_div is greater than Vref_short, and LED_short is at a logic high level, so that an LED channel is in a channel short-circuit state; in the period T2, pwm_1 is at a logic low level, vref_2=vref_open, TG2 transmits a signal, at this time V LED_div > vref_open, led_open is at a logic low level, indicating that the LED channel is not in an open channel state; in the period of T3-T4, both the LED_short and the LED_open are at logic low level, which means that the LED channel is in a normal working state; in the period of T5, V LED_div < Vref_short, and LED_short is at logic low level, which indicates that the LED channel is not in a channel short-circuit state; during period T6, V LED_div < Vref_open, LED_open is at a logic high level, indicating that the LED path is in a path open state.
In summary, according to the LED path state detection circuits 300 and 500 of the embodiments of the present invention, when the LEDs in the LED paths are in the on state, the short circuit/open circuit time division multiplexing detection module is used to implement the short circuit and open circuit determination function of the LED paths through the serial determination mechanism, so that the use of the comparator is reduced and the overall power consumption is reduced.
The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. For example, the algorithms described in particular embodiments may be modified without departing from the basic spirit of the invention. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Claims (10)

1. An LED via status detection circuit comprising:
And a short/open time division multiplexing detection module configured to serially determine whether the LED path is in a path short state and whether the LED path is in a path open state based on a first path voltage, a short determination reference voltage, and an open determination reference voltage of the LED path.
2. The LED via status detection circuit of claim 1, wherein the short/open time division multiplexing detection module is further configured to determine whether the LED via is in a via short state based on the first via voltage and the short determination reference voltage, and determine whether the LED via is in a via open state based on the first via voltage and the open determination reference voltage if it is determined that the LED via is not in a via short state.
3. The LED via status detection circuit of claim 2, wherein the short/open time division multiplexing detection module is further configured to end detection if the LED via is determined to be in a via short state or a via open state.
4. The LED via status detection circuit of claim 1, wherein the short/open time division multiplexing detection module is in an enabled state or a disabled state under control of a pulse width modulated signal for controlling LEDs in the LED via to be on or off.
5. The LED via status detection circuit of claim 4, wherein the short/open time division multiplexing detection module comprises:
A second-choice multiplexer configured to select one of the short circuit judgment reference voltage and the open circuit judgment reference voltage as a judgment reference voltage under control of a frequency division signal of the pulse width modulation signal; and
A short/open judgment multiplexing comparator configured to generate a short state indication signal indicating whether the LED path is in a path short state or an open state indication signal indicating whether the LED path is in a path open state based on the judgment reference voltage and the first path voltage.
6. The LED via status detection circuit of claim 5, wherein the short/open time division multiplexing detection module further comprises:
a first transmission gate configured to output the short-circuit state indication signal under control of a divide-by-two signal of the pulse width modulation signal; and
And a second transmission gate configured to output the open state indication signal under control of an inverted signal of a divide-by-two signal of the pulse width modulation signal.
7. The LED channel state detection circuit of claim 5, wherein the short/open time division multiplexing detection module further comprises a switching tube that is turned on or off under control of the pulse width modulation signal, a first voltage dividing resistor, and a second voltage dividing resistor that divides the first channel voltage when the switching tube is in an on state.
8. The LED channel state detection circuit of claim 7, wherein the short/open determination multiplexing comparator generates the short state indication signal or the open state indication signal based on the divided voltage of the first channel voltage and the determination reference voltage.
9. The LED via status detection circuit of claim 1, further comprising:
a path voltage comparator module configured to determine whether the LED path is in a path voltage deviation state based on a path voltage of the LED path and a voltage deviation reference voltage,
Wherein the first and second path voltages are voltages on the drain and source, respectively, of a high voltage isolation tube connected between the LED path and ground and turned on or off under control of a pulse width modulated signal for controlling the turning on or off of LEDs in the LED path.
10. The LED via status detection circuit of claim 9, wherein the via voltage comparator module is in an enabled state or a disabled state under control of the pulse width modulated signal.
CN202410058980.4A 2024-01-15 2024-01-15 LED (light-emitting diode) access state detection circuit Pending CN117949860A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202410058980.4A CN117949860A (en) 2024-01-15 2024-01-15 LED (light-emitting diode) access state detection circuit

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202410058980.4A CN117949860A (en) 2024-01-15 2024-01-15 LED (light-emitting diode) access state detection circuit

Publications (1)

Publication Number Publication Date
CN117949860A true CN117949860A (en) 2024-04-30

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Family Applications (1)

Application Number Title Priority Date Filing Date
CN202410058980.4A Pending CN117949860A (en) 2024-01-15 2024-01-15 LED (light-emitting diode) access state detection circuit

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